1. Field of the Invention
The present invention relates to an exhaust muffler for a vehicle. In particular, the present invention relates to an exhaust muffler for a vehicle including a communication pipe that establishes communication between an exhaust entrance portion or an exhaust exit portion and muffler chambers formed in the exhaust muffler.
2. Description of the Related Art
Conventionally, what is known is an exhaust muffler for a vehicle including a communication pipe that establishes communication between a plurality of muffler chambers (for example, an expansion chamber, a resonator chamber, a sound absorption chamber or the like) being formed inside, and an exhaust entrance portion or an exhaust exit portion. The communication pipe guides exhaust gas introduced into the exhaust entrance portion to the exhaust exit portion, while reducing exhaust noises by guiding the exhaust gas successively through a plurality of muffler chambers.
With such an exhaust muffler, the communication pipe is inserted into the exhaust entrance portion, and the circumferential portion of a first side is fixed to the opening peripheral portion of the exhaust entrance portion by welding, whereas the circumferential portion of a second side is fixed to a separator or the like that partitions the inside of the exhaust muffler into a plurality of muffler chambers. Further, to the exhaust entrance portion, the rear end portion of the exhaust pipe connected to an exhaust portion of the engine is connected. Thus, exhaust gas discharged from the engine is guided to the exhaust muffler for a vehicle, whereby exhaust noises are reduced. There is Prior Technique Document JP 61-207813 A.
Meanwhile, as methods for connecting the exhaust pipe to the exhaust entrance portion, the following are known: a screwing method with use of a flange; a method in which the rear end portion of the exhaust pipe is flared to be enlarged and fixed by welding to the exhaust entrance portion so as to surround the exhaust entrance portion; a method in which the exhaust pipe is inserted into the communication pipe and fixed by welding at the front end peripheral portion of the communication pipe, and the like. However, every one of these methods necessitates preparing the joining portion separately between the exhaust pipe and the exhaust entrance portion. Accordingly, manufacturing is not easy, and an increase in costs is invited.